Lord Chambers

I saw a Bianchi Volpe listed by someone as a "touring" bike on Craigslist and felt incensed. How dare that person damage my perception of the Volpe as something faster, quicker, and more armstrong than a hipster touring rig. I decided to actually dig through the geometry of several road, touring, and crossbikes to determine whether there were any real differences which would account for this perception that cross and road bikes are faster than touring bikes.

What I found was that everything is basically the same discounting a difference in 1 degree or centimeter here or there. The only noticible differences are that touring bikes are a lot longer via the chainstays and road bikes are a lot shorter in the top tube. Agreed? This brings me to two questions:

1. What about a longer wheelbase (longer chainstays) makes a bike less "agile" or "crisp" like I keep reading about here? I have a couple thousand miles of experience on a Poprad, so am not a complete noobie, but when test riding a Redline Conquest directly after a Long Haul Trucker I don't really notice a difference in how quick I can turn the handlebars. I haven't tried turning around in small spaces, but don't figure that anyone other than the racers on the board have either. So is this so-called "agility" and "twitch" a product of more geometry factors than just wheelbase? If so, what?

2. I was surprised that road bikes generally have shorter top tubes than cross bikes. Why? Wouldn't a longer tube stretch you out more, creating a more aerodynamic position for the rider? Shouldn't road bikes have longer tubes than bikes designed less for speed and more for comfort instead of shorter than touring bikes?

carpediemracing 

I'd disagree with the "longer top tube shorter chainstay" generalization. Touring bikes (i.e. not cross bikes) will also have rack mounts, usually an extra bottle mount or two, and typically have stronger tubes both for construction purposes (need to braze mounts in the thin part of a fork) and/or for load carrying purposes. Touring bikes typically have more clearance for tires so you can mount larger tires for better comfort/durability. Touring bikes will usually be stiffer unloaded - think heavy duty van which bounces along unladen but is very happy and smooth once you put 2000 pounds in it (I have one).

Cross bikes and Touring bikes have similar needs - stability, good top tube clearance, more tire clearance and a bit more strength than a standard road bike. However I would not call them both the same kind of bike, they aren't quite identical, mostly due to the load carrying compromises made on a true Touring bike.

As far as chainstay, twitchiness, etc go, there are a couple factors and a couple things which you'd want to check/test/try:
1. "Twitchiness" or quick turning response for road/race bikes is more a high speed thing. My road bike is not that easy to turn around on a sidewalk, not compared to a BMX bike for example. But at 35 mph, diving into a sharp curve, if I need to make a course adjustment, my road bike is excellent at that. Turn in is a combination of trail (less is twitchy) and wheelbase. I also think (but have no proof) that weighting the front wheel more helps, so a shorter TT + long stem + short stays helps get the weight over the front wheel.

2. Trail is not just less rake in a fork. In fact, for many bikes, increasing rake reduces trail. Counterintuitive I suppose (it is to me) but that's the way trail works. The only time this is not true is if the headtube angle is 90 deg or greater - like derny race bikes (they have 90 degree headtube angles), shopping cart wheels (ditto). Then a negative rake (think shopping cart wheel going forward - the "wheel" axle is behind the pivot axle) is more stable.

3. Short stays allows a standing rider to exert more pressure on the pedals without worrying about rear tire slippage, like during sprints. I had to compromise my forward sprinting style when I had my first (relatively long chainstay) Cannondale "race" frame. I look for extremely short chainstays because I prefer to be way over the front wheel when sprinting, and short stays help with that. Short stays also help maintain traction on very steep hills when standing.

To assuage your Volpe pride, I don't know what era Volpe you have, but the Volpes I'm familiar with date from almost 20 years ago. They were fantastic cross type bikes, cables up high out of the mud, cantilevers, nice drivetrains. If I were to tour on a bike, I may choose a Volpe over a "true" Touring bike.

hope this helps,
cdr

alanbikehouston

An "aero" position is helpful at 35 mph. It is not helpful at 15 mph. Getting your body into an aero position is largely controlled by the "drop" from the saddle to the bars. Comfort (and comfort is the key to doing a lot of daily miles) is controlled by NOT having much drop from the saddle to the bars.

This year, Paris-Roubaix was won with a bike that was designed for fat tires and a higher bar position...the classic design features of a "touring bike". The winning cyclist said "If I am comfortable, I can ride faster".

In other words, unless you are in a short time-trial on a smooth road going 35 mph, don't obsess about an extreme "aero" position.

meanwhile

"Faster" means is quite complex for a bicycle. Bike A might be faster than B on a mediocre road with 150W of rider power but slower on a smooth road at 250W. Bike C might out-accelerate both while having a lower max than either, which might make it a faster commute bike. Bike D might be slightly slower than A or B solo, but be a better bike to ride in TDF style racing because they handle log dogs while handles superbly for tucking in and breaking away.

You wouldn't. The idea is that a short wheelbase makes the back wheel respond more quickly to orders from the front wheel, at the cost of a twitchier ride. Shorter is good for bikes that take part in TDF style events, or Criterions with fast twitchy courses.

Good tyres help. Smaller wheels make for much more agile bikes - good hardtail MTBs with slicks can make 700c racers seem like dogs, and 20 inch folder and BMXs can be extraordinary.

Road racers are probably still stretched out more than crossers, but they get more length in the stem. Crossers need short stems to gain more steering control. Also, length in the top tube rather than the stem gives more leverage for the riders weight to keep the rear wheel down during braking on descents - an urgent need for crossers.

Longfemur

I'm not an aero weanie by any means, but let's keep in mind that it doesn't just matter when going very fast. It matters when riding into wind too, even at slower speeds.

No, it's not a long top tube that makes for aero, it's the rider's position, and this is accomplished by the length of the stem. It used to be that even racing bikes were long with a relatively short stem compared to today's, but that started changing in Eddy Merckx's time --- shorter bike but with longer stem.

But if you were to ride fast under all kinds of different conditions, you would find that a touring bike's handling is in no way comparable to that of a more racing-oriented bike. It's not inferior though. It just depends what you want and your goal is.

meanwhile

That's very interesting. How fat? 28? 32?

Something a lot of people don't understand is that rolling resistance is lower for wider tyres all things being equal - although this can be more than made up for by extra drag in really fast racing.

big john

Touring bikes also have long chainstays to prevent the riders heel from hitting the panniers. A long wheelbase on any vehicle rides smoother than a short one.
Choose your frame size based on top tube length rather than seat tube. For example, just because you ride a 58cm brand x road bike doesn't mean you will fit a 58cm cross or touring bike.

simplyred

Sure. But at what point do you start to lose power due to inefficient position when you are stretched out like Superman?

Shorter top tube [for road bikes/TT frames] - smaller triangles give a "stiffer" frame, less material req'd, can fit more people [ie. change of stem].

Oh - and touring bikes generally have taller headtubes - so less drop allowable, negating possible aero-ness

StanSeven

That isn't true. All it takes is experimenting with positions on a flat road with a powermeter. With the same power, you'll find a noticable change of speed just switching bewteen the hoods and drops even going as slow as 15 mph.

climbhoser

Re: longer chainstays-



Good for heel clearance, good for overall stability, but there's also more flex in them, which saps power especially when really crankin'. Short chainstays of any material will lose less power from the pedal input.



Another reason 'cross bikes of a similar size seem to have longer TTs is that these days most crossers will go down a size. So, you ride a 58 road cycle you'll probably get on a 56 'cross bike. Then you actually either have the same TT or maybe shorter than your road bike. 'Crossers do this to decrease standover height while still keeping traditional style frames (more convenient for carry sections).



Some 'cross bikes don't really fit this bill, though, and that's a bike like the Surly Crosscheck, which just has insane geometry, IMHO. I mean, the 56 has a 57cm top tube, but only a freakin' 12.5cm headtube! That's insanity! Most road frames of the same size will have at least 3 cm more in head tube. So, don't take a bike like the Cross Check as gospel for 'cross bikes.



Another thing to note about 'cross bikes is a higher BB for tight cornering clearance. This is also aided by a longer chainstay.



Longer chainstays also give more tire clearance (crucial).



Anyways, all bikes are about getting comfortable, and you can't just look at traditional sizing and geometry and try and make conclusions like this. There is a lot that goes into it, and it's different company to company.

meanwhile

This is one of those things that people believe which there seems to be absolutely no evidence for anywhere. I suspect that people worry over this rather than eg having as few links in a chain as possible to reduce mechanical losses solely because marketing by bike companies has equated frame "tautness" with efficiency. Although again evidence seems t be lacking.

meanwhile

What does "noticeable" mean? The figures I've seen show that drops can do something like change a speed of 20mph into 22. Remembering that air resistance is a speed cubed thing, that suggests that you'd need a flat windless road and a closely watched digital speedo to see a difference at 15mph, unless you were cyvling into the wind.

justinb

Here's Tom Boonen's "touring" bike, with 5" of saddle to bar drop, and 26mm tubies.

StephenH

https://www.sheldonbrown.com/images/Solotand-BS.JPEG

Lord Chambers

True. I forgot to rule out these kinds of differences so we could focus just on the geometry. Why is there such a widespread conception of distinct uses and strengths for road, cross, and touring bikes when they are 90% alike? Brazeons and eyelets aren't keeping people from winning races. The only major differences I can spot other than stock gearing are the geometric differences I mentioned, which I still don't understand fully enough to see how a shorter tube can make someone a winner, but a lower bottom bracket make him a loser. Where do these perceptions come from?

If it's the gearing that makes the difference then why don't we talk more about triples vs. doubles and mountain bike gearing vs. road gearing when people come asking questions about which bike is for them?

If it's a sum of all these small centimeters and degrees, eyelets and gears that make for such distinct categories as ROAD, CROSS, TOURING, then I guess I accept that just like everyone else. But that doesn't mean I won't continue to question it.

At the end of the day I just want a bike with gearing and mounts that'll let me tour loaded, but for the other 330 days of the year is fast as **** and will let me zoom up hills and zip past friends. After lifting a Volpe and a Poprad at the LBS, I was crushed to find that two same size steel frames are vastly different weights. Then seeing the Volpe listed as a touring bike made me rethink whether I could really find this perfect bike for me, and if I should just settle for a touring bike which is so routinely described as "stable" and not "fast." I guess I'm looking to geometry as a last ditch ploy to find a bike I can see as "aggressive" and "fast" even when its got a triple.

It's an anecdote, but check this out:
Here's a "touring" bike with a 42cm chainstay: https://www.bikesdirect.com/products/...rist.htm#specs
Here's a "cross" bike with a 44cm chainstay: https://www.specialized.com/bc/SBCBkModel.jsp?spid=22307
These categories almost led me to buying the heavy touring bike Bianchi sells as a cross bike because I thought "cross" bikes were faster.

Why?

big john

If you had a B.O.B. trailer, you could tour with any bike. There were 8 of us unsupported, but not camping, and the ladies had seatpost racks and backpacks. 2 of us had touring bikes, and 2 guys took turns pulling the trailer.

climbhoser

[QUOTE=Lord Chambers;7075616]At the end of the day I just want a bike with gearing and mounts that'll let me tour loaded, but for the other 330 days of the year is fast as **** and will let me zoom up hills and zip past friends. After lifting a Volpe and a Poprad at the LBS, I was crushed to find that two same size steel frames are vastly different weights. Then seeing the Volpe listed as a touring bike made me rethink whether I could really find this perfect bike for me, and if I should just settle for a touring bike which is so routinely described as "stable" and not "fast." I guess I'm looking to geometry as a last ditch ploy to find a bike I can see as "aggressive" and "fast" even when its got a triple./QUOTE]

Answer is the Soma Double Cross.

It has pretty sleek geometry, only 425 chainstays which will keep it zippy feeling, but it has eyelets and braze ons front AND rear.

The question you have to ask is will you have heel strike with panniers, because that's what most touring bikes alleviate. I know with the right panniers and the right rack I NEVER have heel strike on my Surly Crosscheck which has 425 long chainstays. And they're good panniers, too, with plenty of space.

The Double Cross feels pretty roadie-rific with the right tires on, though.

As to why Cross Check did that with their geometry my belief is twofold:

1) guys were sizing down road bikes to get a cross bike with better standover, but were then having to use super long stems to compensate. Surly did them a favor and gave them horizontal top tubes, lower standover, but adequate top tube.

2) the headtube length problem, my belief is they did this because they figgered most guys prefer flipped up stems when riding 'cross anyways (it does make it feel less twitchy) and maybe a spacer or two wouldn't be so bad.

In all honesty the headtube length isn't a problem for the anatomically normal, but for guys like me with short arms and long legs it is a BIG problem. Not only is the TT too long, but the HT is too short! Go down a size and the TT is more reasonable, but the HT is WAY too short!

Oh yeah, and I guess one more reason they helped justify it with is that 'cross bikes typially utilize longer forks, like a 400mm on the Crosscheck. That actually jacks your overall bar height up about 3-5cm from your typical road fork anyways. So, in essence a road bike with a 155mm TT and a 365mm fork is like a 'cross bike with a 120mmTT and a 400mm fork. However, in my experience that sounds great on paper, but it doesn't quite work out that way. I've yet to figure out why, but when I get on a road bike with a 365 fork and a 155 HT I feel way higher than the Crosscheck

zzzwillzzz

one thing i haven't seen anyone mention is that the top tube should not dictate your position. if you had to choose between two bikes for the same purpose, the first with a 57cm top tube and the second with a 55cm top tube you would choose different stems for each bike to put you in the same position. if you need a 100mm stem for the first then you would use a 120mm on the other to put you in the same position (ignoring any height difference between the two for the moment). so no it wouldn't make it any more aerodynamic.

dutret

With a horz tt the length of the ht is meaningless. By raising the bb or shortening the fork all points of contact remain the same while the ht length increases.

Lord Chambers

Understood. This is why I have a hard time buying the argument that some bikes’s geometry are more aggressive while others are more upright. Among touring, cross, and road bikes, they have virtually identical measurements where it would affect your posture: the seat to handlebar distance. The places they diverge (top tube, chain stays, bottom bracket) may affect handling in some way that is undetectable to me during a 10 minute test ride outside the bike shop, but don't affect your position on the bike. In other words, on a paved straightaway I should be able to outride roadies with the right tires on a cross bike, and able to outride fat roadies with the right tires on a touring bike.

climbhoser

Length of HT is never meaningless! It's just relative, and I think that's what you're saying. Yeah, you have to take BB height/drop into acct., which I didn't cover. So a Surly Xcheck does have a high BB, with a drop of only 66mm, but let's contrast that with a more racer-ish geometry like the Soma Smoothie (still a heavy, utilitarian bike with eyelets and braze-ons). The Soma has a BB drop of 70mm. Someone might say that's noticeable, but it's only .5cm and really won't effect overall contact points that much.

Xcheck has 40cm fork and a 12.5cm HT on the 56 size. That puts the top at 52.5cm. Soma Smoothie has a 36.5cm fork and a 15.5cm HT which puts you at 52cm top. Your but will be .5cm lower on the Smoothie because of BB drop. Not a big difference, but ultimately the TT is 1cm shorter.